Speedwork - 8 x 1 mile repeats (but ended up 6) (7.5 miles total)

We did speedwork at TD Waterhouse Stadium today. After our 1.5 mile warm up, the goal was to do 8 x 1 mile repeats (4 times around the track). But after 5 repeats, my left calf and right hamstring were both very tight, and I didn't want to risk damaging them, so I did a slow mile and then pulled the plug on the night. Here were my times:

6:49
6:52
6:50
6:52
6:53
7:35

So my average for the first 5 repeats was pretty quick, for me: 6:51. But I pulled the plug on the speedwork after those 5 because I was afraid I'd damage a muscle or hamstring or something. Anyhow, including the warm-up miles, I did about 7.5 miles tonight